Close-coupled step-up voltage converter and electrode for a combustion system

ABSTRACT

A high voltage signal is output to an electrode, which applies electrical energy to a combustion reaction. The high voltage signal can be output by a step-up voltage converter to the electrode via a close electrical coupling. The close electrical coupling is configured to electrically isolate the high voltage signal from a human-accessible volume.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority benefit from U.S. Provisional Patent Application No. 61/702,360, entitled “CLOSE-COUPLED STEP-UP VOLTAGE CONVERTER AND ELECTRODE FOR A COMBUSTION SYSTEM”, filed Sep. 18, 2012; which, to the extent not inconsistent with the disclosure herein, is incorporated by reference.

BACKGROUND

One or more voltages or charge densities can be driven onto or proximate to a combustion reaction using one or more electrodes. For heat output applications of a few hundred thousand BTU per hour, high voltages in the range of 10 kilovolts (kV) to 40 kV can be used to achieve some effects. The voltages or charge densities can be used to achieve a variety of desired effects associated with the combustion reaction and/or apparatuses that receive heat or flue gas from the combustion reaction.

SUMMARY

In electronic combustion control (ECC) systems, high voltage is frequently present on multiple charge elements that are positioned within a combustion chamber and adjacent to, or in contact with a jet of fuel and oxidizer that supports a combustion reaction such as a flame. Meanwhile, systems configured to generate the high voltage and to transmit the high voltage signal to the charge elements may be positioned in a volume of space surrounding the combustion chamber and separated therefrom by the walls of the burner or combustion chamber. The inventors have recognized that high voltages used in proximity to combustion systems may present significant risk of electrocution, fire, static discharge, and other hazards to living organisms, fuel systems, electronics, etc. The present disclosure appreciates that the risks associated with employing high voltages in conjunction with combustion reactions may be greater, or at least may be perceived to be greater than risks associated with other high voltage systems.

According to an embodiment, a system applies electrical energy to a combustion reaction. The system includes a step-up voltage converter and electrode configured for applying the electrical energy to the combustion reaction. The step-up voltage converter is close-coupled to the electrode. The step-up voltage converter is configured to receive a low voltage signal, such as, for example, a low voltage or medium voltage signal on an input node from an electrode controller. The step-up voltage converter is configured to convert the low voltage signal to a high voltage signal, and to output the high voltage signal on an output node of the step-up voltage converter. A close electrical coupling is operatively coupled between the output node of the step-up voltage converter and the electrode. The close electrical coupling is configured to prevent or limit high voltage exposure to a volume that may be, at least intermittently, occupied by a person.

According to an embodiment, a method for applying electrical energy to a combustion reaction includes receiving a low voltage signal at an input node, converting the low voltage signal to a high voltage signal, outputting the high voltage signal on an output node via a close coupling. The electrode is configured to carry the high voltage signal to the combustion reaction. The electrode may also be configured to carry the high voltage signal to proximity with the combustion reaction. The method includes isolating the high voltage signal from an accessible volume separated from the combustion reaction by a combustor or burner wall. Converting the low voltage signal to a high voltage signal can include increasing the voltage by 5 times or more.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system for applying electrical energy to a combustion reaction including a close-coupled step-up voltage converter and an electrode, according to an embodiment.

FIG. 2 is a diagram of an assembly forming a portion of the system of FIG. 1, wherein the close-coupled step-up voltage converter and the electrode can be operatively coupled by a close electrical coupling including a high voltage cable, according to an embodiment.

FIG. 3 is a diagram of an assembly forming a portion of the system of FIG. 1, wherein the close-coupled step-up voltage converter and the electrode can be operatively coupled by a close electrical coupling including a high voltage electrical connection that can be substantially contained by an electrically isolating housing, according to an embodiment.

FIG. 4 is a diagram of an assembly forming a portion of the system of FIG. 1, including an electrically isolating housing that can be configured to mount onto an electrode proximate to a combustor or burner wall such that the high voltage output by the step-up voltage converter can be isolated from a human-accessible volume, for example, when the housing is removed from the electrode, according to another embodiment.

FIG. 5 is a flow chart illustrating a method for applying electrical energy to a combustion reaction, outputting a high voltage signal for an electrode, and isolating the high voltage signal from an accessible volume, according to an embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the disclosure.

FIG. 1 is a block diagram of a system 100 for applying electrical energy to a combustion reaction 104, according to an embodiment. The system 100 includes a step-up voltage converter 106 and an electrode 102. The electrode 102 is configured to apply a charge to the combustion reaction 104.

According to an embodiment, the step-up voltage converter 106 is close-coupled to the electrode 102. The step-up voltage converter 106 is configured to receive a low voltage signal on an input node 108 from an electrode controller 110. The step-up voltage converter 106 converts the low voltage signal to a high voltage signal of 1000 volts or more. The step-up voltage converter 106 is configured to output the high voltage signal on an output node 112 of the step-up voltage converter. Additionally or alternatively, the step-up voltage converter 106 is configured to output the high voltage signal on the output node 112 with a close electrical coupling 114 between the output node 112 of the step-up voltage converter 106 and the electrode 102.

According to an embodiment, the step-up voltage converter 106 includes a voltage multiplier. Other types of step-up voltage converters are contemplated. For example, the step-up voltage converter 106 may include stacked rectifiers, a switching power supply, a linear power supply, and/or a transformer. The step-up voltage converter 106 may provide a high voltage signal on the output node 112 that is at least ten times the magnitude of the voltage signal on the input node 108. Additionally or alternatively, the high voltage signal may be at least one hundred times the magnitude of the voltage signal on the input node 108. Additionally or alternatively, the high voltage signal may be at least one thousand times the magnitude of the voltage signal on the input node 108.

According to an embodiment, the step-up voltage converter 106 is configured to receive a low voltage signal of 960 volts or less from the electrode controller 110. Additionally or alternatively, the step-up voltage converter 106 may be configured to receive a low voltage signal of 240 volts or less from the electrode controller 110. Additionally or alternatively, the step-up voltage converter may be configured to receive a low voltage signal of 120 volts or less from the electrode controller. Additionally or alternatively, the step-up voltage converter may be configured to receive a low voltage signal of 12 volts or less from the electrode controller. Additionally or alternatively, the step-up voltage converter may be configured to receive a low voltage signal of 5 volts or less from the electrode controller.

The electrode controller 110 is operatively coupled to the step-up voltage converter 106. A low voltage cable 111 is configured to carry the low voltage signal from the electrode controller 110 to the step-up voltage converter 106. The low voltage cable 111 includes a first low voltage conductor 111 a configured to carry current corresponding to the low voltage signal from the electrode controller 110 to the step-up voltage converter 106. The low voltage cable 111 includes a second low voltage conductor 111 b configured to carry current corresponding to the low voltage signal from the step-up voltage converter 106 to the electrode controller 110. The first and second low voltage conductors 111 a and 111 b can be configured to minimize stored magnetic energy corresponding to the current carried by the low voltage cable 111.

The high voltage signal applied to a combustion reaction 104 is typically quite a low current. For example, in experiments conducted by the inventors, it was found that approximately 300,000 BTU/hour flames 104 (a flame is a type of combustion reaction) were stabilized by 40,000 volts applied to the electrode 102, and current was in the range of hundreds of microamperes. Ignoring efficiency effects, the low voltage cables 111 a and 111 b carrying power at 40 volts to a 1000× step-up voltage converter 106 delivering 40,000 volts at 100 microamperes of current would carry 1000 times the current, or 100 milliamperes. In a given conductor, higher amperage corresponds to higher inductive (magnetic) energy storage.

To maximize safety (e.g., to minimize voltage switch-off time as described below), it may be advantageous to configure the voltage conductors 111 a and 111 b to minimize stored magnetic energy. In an embodiment, the first and second low voltage conductors 111 a and 111 b are configured to minimize stored magnetic energy corresponding to the current carried by the low voltage cable 111 by being placed within 1 centimeter of one another along a majority of their respective lengths. Placing the first and second low voltage conductors 111 a and 111 b close together can reduce the number of magnetic field lines that will fit between the first and second low voltage conductors 111 a and 111 b. Reducing magnetic field lines will tend to reduce stored magnetic field energy. Reducing stored magnetic energy, in turn, will reduce the amount of time needed to switch off the current delivered to and by components between the electrode controller 110 and the electrode 102.

In an embodiment, the first and second low voltage conductors 111 a and 111 b are configured to minimize stored magnetic energy corresponding to the current carried by the low voltage cable 111 by having respective high aspect ratio cross-sections of 2:1 or greater, and with longer dimensions abutting one another. Placing the first and second low voltage conductors 111 a and 111 b with longer dimensions abutting one another causes magnetic field lines between the first and second low voltage conductors 111 a and 111 b to be longer. Longer magnetic field lines reduce stored magnetic field energy. In other words, the conductors 111 a, 111 b can be arranged, in cross-section, as “∥I” rather than as “••” or “--”. Of the three arrangements shown, and assuming equal spacing between the conductors in each example, arranging the conductors 111 a, 111 b according to the first example (“∥”) minimizes the stored magnetic field energy, relative to the other examples.

According to an embodiment, the electrode controller 110 is configured to output a substantially constant low voltage signal. Additionally or alternatively, the electrode controller 110 can be configured to output a time-varying low voltage signal. The time-varying low voltage signal can include a periodic waveform such as an AC waveform, for example.

According to an embodiment, the high voltage signal can have a voltage of 5000 volts or more. Additionally or alternatively, the high voltage signal can have a voltage of 10,000 volts or more. Additionally or alternatively, the high voltage signal can have a voltage of 40,000 volts or more. Additionally or alternatively, the high voltage signal can have a negative voltage of magnitude 1000 volts or more. Additionally or alternatively, the high voltage signal can have a negative voltage of magnitude 5000 volts or more. Additionally or alternatively, the high voltage signal can have a negative voltage of magnitude 10,000 volts or more. Additionally or alternatively, the high voltage signal can have a negative voltage of magnitude 40,000 volts or more.

According to an embodiment, the close electrical coupling 114 is configured to limit or prevent high voltage exposure to a volume that may be at least intermittently occupied by a person.

FIG. 2 is a diagram of an assembly 200 forming a portion of the system 100 of FIG. 1. In the assembly 200, the close-coupled step-up voltage converter 106 and the electrode 102 is operatively coupled by a close electrical coupling 114 including a high voltage cable 202, according to an embodiment. The close electrical coupling 114 includes a high voltage cable 202 having a length of 2 meters or less. Additionally or alternatively, the close electrical coupling 114 may include a high voltage cable 202 having a length of 10 centimeters or less.

According to an embodiment, the step-up voltage converter 106 is configured for mounting on or near a combustor or burner wall 204. The electrode 102, or a connection 206 in electrical continuity with the electrode 102, is configured to penetrate the combustor or burner wall 204 to cause at least a portion of the electrode 102 to be in proximity to the combustion reaction 104.

In an embodiment, a connection 206 is in electrical continuity with the electrode 102 and is configured to penetrate the combustor or burner wall 204 to cause at least a portion of the electrode 102 to be in proximity to the combustion reaction 104. The close electrical coupling 114 can include a high voltage cable 202 configured to carry the high voltage signal from the output node 112 to the electrode 102, or the connection 206, in electrical continuity with the electrode 102.

In an embodiment, the close electrical coupling 114 includes an electrically isolating housing 208 configured to be electrically isolating. In an embodiment, the close electrical coupling 114 includes a housing 208 configured to electrically isolate the high voltage cable 202 from a region separated from the combustion reaction 104 by the combustor or burner wall 204. Additionally or alternatively, the close electrical coupling 114 can include the housing 208 configured to electrically insulate the high voltage cable 202 from a region separated from the combustion reaction 104 by the combustor or burner wall 204. Additionally or alternatively, the close electrical coupling 114 can include the housing 208 configured to electrically isolate the high voltage cable 202 from a region separated from the combustion reaction 104 by the combustor or burner wall 204. Additionally or alternatively, the close electrical coupling 114 can include an electrically grounded housing 208 configured to isolate the high voltage cable 202 from a region separated from the combustion reaction 104 by the combustor or burner wall 204.

FIG. 3 is a diagram of an assembly 300 forming a portion of the system 100 of FIG. 1, according to an embodiment. The close-coupled step-up voltage converter 106 and the electrode 102 can be operatively coupled by a close electrical coupling 114. According to an embodiment, assembly 300 includes a high voltage electrical connection 304 that can be substantially contained by an electrically isolating and/or grounded housing 208.

According to an embodiment, the close electrical coupling 114 includes a high voltage cable 202 configured to withstand a temperature elevation caused by conduction of heat from the combustion reaction 104 to the high voltage cable 202 by the electrode 102. Additionally or alternatively, the close electrical coupling 114 can include a high voltage electrical connection 304 configured to withstand a temperature elevation caused by conduction of heat from the combustion reaction 104 to the high voltage electrical connection 304 by the electrode 102. Additionally or alternatively, the close electrical coupling 114 can include a high voltage cable 202 and a high voltage electrical connection 304 configured to withstand a temperature elevation caused by conduction of heat from the combustion reaction 104 to the high voltage cable 202 and a high voltage electrical connection 304 by the electrode 102.

According to an embodiment, a high voltage control switch 314 is configured to cause the step-up voltage converter 106 not to output the high voltage to the conductive output surface 312 when the electrically isolating housing 208 is moved from a position that isolates the high voltage signal from the accessible volume 307.

For example, the electrically isolating housing 208 can be configured to mount onto a combustor or burner wall 204 such that the high voltage output node 112 of the step-up voltage converter 106 is electrically isolated from an accessible volume 307 separated from the combustion reaction 104 by the combustor or burner wall 204. The accessible volume 307 can include a volume at least intermittently occupied by a person.

In an embodiment, the assembly 300 including the electrically isolating or grounded housing 208, the step-up voltage converter 106, and the high voltage electrical connection 304 are integrated with the electrode 102. To change the electrode 102, the input node 108 is first disconnected from continuity with the electrode controller 110 (see FIG. 1), and the assembly is removed from the combustor or burner wall 204. During operation, the high voltage carried by the high voltage electrical connection 304 and the electrode 102 is insulated and/or isolated from the accessible volume 307 separated from the combustion reaction 104 by the combustor or burner wall 204. The high voltage carried by the high voltage electrical connection 304 and the electrode 102 are also isolated from objects and/or persons that represent a risk and/or danger of electrical discharge to objects and or persons in the accessible volume 307 separated from the combustion reaction 104 by the combustor or burner wall 204. Optionally, a switch 314 may be configured to sense when the electrically isolating housing 208 is moved from a position that isolates the high voltage signal from the accessible volume 307, and to shut down the step-up voltage converter 106 before the housing 208 is fully removed, in order to prevent accidental contact with a high-voltage-charged element.

FIG. 4 is a diagram of an assembly 400 that forms a portion of the system 100 of FIG. 1, according to an embodiment. The assembly 400 includes an electrically isolating or grounded housing 208 that is configured to mount onto an electrode 102 proximate to a combustor or burner wall 204 such that the high voltage output by the step-up voltage converter 106 is isolated from a human-accessible volume 307 when the electrically isolating housing is mounted on the electrode 102.

In an embodiment, electrode 102 includes a conductive electrode surface 402 configured to receive the high voltage. Electrode 102 includes an electrode coupling feature 404. The close electrical coupling 114 includes a close electrical coupling feature 406 configured to receive or otherwise couple to the electrode coupling feature 404. The close electrical coupling feature 406 can include a prong, a socket, or other feature matched to (e.g., complementary to) the electrode coupling feature 404, and includes an electrically conductive output surface 312 configured to hold or be held in a contacting relationship with the electrode coupling feature 404 of the electrode 102. The close electrical coupling feature 406 may also be referred to as an “electrode socket”. It will be understood that the term “electrode socket” does not imply a male or female relationship with respect to the electrode and its electrode coupling feature 404.

The electrode 102 includes a conductive electrode surface 402 configured to receive the high voltage. The close electrical coupling feature 406 further includes a conductive output surface 312 configured to output the high voltage. A high voltage control switch 314 is configured to cause the step-up voltage converter 106 not to output the high voltage to the conductive output surface 312 when at least a portion of the conductive electrode surface 402 is not in contact with at least a portion of the conductive output surface 312. A high voltage control switch 314 includes a momentary switch configured to be held normally open when at least a portion of the conductive electrode surface 402 is not in contact with at least a portion of the conductive output surface 312. Additionally or alternatively, the high voltage control switch 314 can include a momentary switch configured to be open when the high voltage signal is not isolated from an accessible volume 307.

According to an embodiment, the high voltage control switch 314 includes at least a portion that is mechanical. Additionally or alternatively, the high voltage control switch 314 can be a non-mechanical switch. Examples of the high voltage control switch include a reed switch, a mercury switch, an integrated circuit, and/or an integrated switch.

According to an embodiment, the electrode 102 includes a conductive electrode surface 402 configured to receive the high voltage. The close coupling includes a conductive output surface 312 configured to output the high voltage. The high voltage control switch 314 is configured to cause the close coupling not to output the high voltage to the conductive output surface 312 when at least a portion of the conductive electrode surface 402 is not in contact with at least a portion of the conductive output surface 312.

FIG. 4 is a diagram of an assembly 400 including an electrically isolating housing 208 configured to mount onto an electrode 102 proximate to a combustor or burner wall 204 such that the high voltage output by the step-up voltage converter 106 is isolated from the accessible volume 307 separated from the combustion reaction 104 by the combustor or burner wall 204, according to an embodiment. The assembly 400 including the electrically isolating housing 208, the step-up voltage converter 106, and the high voltage electrical connection 304 can be configured for coupling to the electrode 102.

In an embodiment, to change the electrode 102, portions of the assembly 400 including the housing 208, the input node 108, the control switch 314, the step-up voltage converter 106, and the close electrode coupling feature (also referred to as the electrode socket) 406 are removed from the electrode coupling feature 404. The high voltage control switch 314 causes the conductive output surface 312 to not carry the high voltage after the close electrical coupling feature 406 is partially removed from the electrode coupling feature 404. The electrode 102 can then be removed from the combustor or burner wall 204. The electrically isolating housing 208 can optionally be configured to cover electrode mounting features for mounting the electrode 102 to the combustor or burner wall 204 when the electrically isolating housing 208 is mounted on the electrode 102. During operation, the high voltage carried by the high voltage electrical connection 304 and the electrode 102 is isolated from the accessible volume 307 separated from the combustion reaction 104 by the combustor or burner wall 204 and from objects and/or persons that represent a risk and/or danger of electrical discharge to objects and or persons in the accessible volume 307.

FIG. 5 is a flow chart illustrating a method 500 for applying electrical energy to a combustion reaction. The method 500 includes a high voltage signal output for an electrode. The method 500 also includes isolating the high voltage signal from an accessible volume, according to an embodiment.

The flow chart in FIG. 5 illustrates a method 500 for applying a voltage to a combustion reaction, according to an embodiment. Additionally or alternatively, it illustrates a method 500 for applying electrical energy to the combustion reaction. Additionally or alternatively, it illustrates a method 500 for applying an electric field to the combustion reaction.

In an embodiment, the method 500 includes step 504, in which a low voltage signal is received at an input node. In step 506 the low voltage signal is converted to a high voltage signal of about 1000 volts or more. Continuing to step 508 the high voltage signal is output on an output node for an electrode configured to carry the high voltage signal to a combustion reaction. Additionally or alternatively, step 508 can output the high voltage signal on the output node for the electrode configured to carry the high voltage signal to proximity with the combustion reaction. In step 510 the high voltage signal is carried with a close electrical coupling. Proceeding to step 512 the high voltage signal is isolated from an accessible volume separated from the combustion reaction by a combustor or burner wall.

In respective embodiments, in step 506, the low voltage signal conversion to the high voltage signal includes increasing the voltage by more than 5 times, more than 100 times, and more than 1000 times.

In an embodiment, the step 506 converts the low voltage signal to the high voltage signal of about 1000 volts or more and may include operating a voltage multiplier. Additionally or alternatively, step 506 can include operating a rectifier stack, operating a switching power supply, operating a linear power supply, and/or operating a transformer.

In an embodiment, the low voltage signal received at the input node in step 504 includes receiving a signal of 960 volts or less. Additionally or alternatively, the low voltage signal received at an input node in step 504 includes receiving a signal of 240 volts or less. Step 504 can also include receiving a signal of 12 volts or less. Step 504 can further include receiving a signal of 5 volts or less. Step 504 can include receiving the low voltage signal from an electrode controller.

In an embodiment, step 502 includes outputting the low voltage signal from an electrode controller. The low voltage signal output from the electrode controller can be a substantially constant low voltage signal. Additionally or alternatively, the low voltage signal output from the electrode controller 110 can be a time-varying low voltage signal. The low voltage signal output from the electrode controller 110 can include a periodic waveform. For example, the low voltage signal output from the electrode controller 110 can include a modulated DC signal, an AC signal, and/or an AC signal biased by a DC signal.

In an embodiment, in step 508 the high voltage signal output can be 5000 volts or more. Additionally or alternatively, outputting the high voltage signal output can include outputting the high voltage signal at a voltage of 10,000 volts or more.

In an embodiment, outputting the high voltage signal includes outputting the high voltage signal at a voltage of 40,000 volts or more. Outputting the high voltage signal can include outputting the high voltage signal at a negative voltage of magnitude 1000 volts or more. Outputting the high voltage signal can include outputting the high voltage signal at a negative voltage of magnitude 5000 volts or more. Outputting the high voltage signal can include outputting the high voltage signal at a negative voltage of magnitude 10,000 volts or more. Outputting the high voltage signal can include outputting the high voltage signal at a negative voltage of magnitude 40,000 volts or more.

In an embodiment, step 510 includes carrying the high voltage signal from the output node to the electrode via a close electrical coupling. The close electrical coupling can be configured to prevent high voltage exposure to a volume at least intermittently occupied by a person. Carrying the high voltage signal to the electrode via the close electrical coupling can include outputting the high voltage signal to the electrode via a high voltage cable having a length of 2 meters or less. Additionally or alternatively, outputting the high voltage signal to the electrode via the close electrical coupling can include outputting the high voltage signal to the electrode via a high voltage cable having a length of 10 centimeters or less.

In an embodiment, step 506 for converting the low voltage signal to the high voltage signal includes converting the low voltage signal to a high voltage signal with a step-up voltage converter configured for mounting on or near a combustor or burner wall. The electrode, or a connection in electrical continuity with the electrode, can be configured to penetrate the combustor or burner wall to cause at least a portion of the electrode to be in proximity to the combustion reaction.

In an embodiment, step 510 includes carrying the high voltage signal from the output node to the electrode via a close electrical coupling. For example, step 510 can include carrying the high voltage signal with a high voltage cable to the electrode. Additionally or alternatively, step 510 can include carrying the high voltage signal with a high voltage cable to the connection in electrical continuity with the electrode.

In an embodiment, step 512 includes isolating the high voltage signal. Step 510 can include providing an electrically isolating and/or grounded housing configured to isolate the high voltage cable from a region separated from the combustion reaction by a combustor or burner wall.

In an embodiment, step 512 includes isolating the high voltage signal from an accessible volume separated from the combustion reaction by a combustor or burner wall. According to an embodiment, step 512 includes housing the step-up voltage converter in or behind an electrically isolating housing.

In an embodiment, step 510 includes carrying the high voltage signal from the output node to the electrode via a close electrical coupling. Step 510 can include carrying the high voltage signal from the output node to the electrode via a high voltage electrical connection that is substantially contained by the electrically isolating housing. Step 510 for carrying the high voltage signal from the output node to the electrode via the close electrical coupling can include carrying the high voltage signal on a shielded electrode configured to minimize electromagnetic interference.

In an embodiment, carrying the high voltage signal from the output node to the electrode via a close electrical coupling includes carrying the signal as a multiplexed signal configured for selective output using a multiplexed array of resonant electrodes.

In an embodiment, carrying the high voltage signal from the output node to the electrode via a close electrical coupling includes carrying the high voltage signal in an electrically isolated volume. Carrying the high voltage signal from the output node to the electrode via a close electrical coupling can include carrying the high voltage signal inside a Faraday cage.

In an embodiment, carrying the high voltage signal from the output node to the electrode via a close electrical coupling includes carrying the high voltage signal in an electrically isolating housing. Carrying the high voltage signal from the output node to the electrode via a close electrical coupling can include carrying the high voltage signal in a grounded conduit. Carrying the high voltage signal from the output node to the electrode via a close electrical coupling can include carrying the high voltage signal on an output node including a shielded cable.

In an embodiment, step 510 includes carrying the high voltage signal on an output node including a high voltage electrical connection that is substantially contained by the electrically isolating housing.

In an embodiment, Step 514 includes receiving a high voltage control signal at a high voltage control switch. The high voltage control switch can be configured to respond, for example, when isolation between a node carrying the high voltage signal and a volume separated from the combustion reaction by a combustor or burner wall is interrupted. In another example, the switch is configured to respond when insulation between a node carrying the high voltage signal and a volume separated from the combustion reaction by a combustor or burner wall is interrupted. In another example, the switch is configured to respond when isolation and insulation between a node carrying the high voltage signal and a volume separated from the combustion reaction by a combustor or burner wall is interrupted.

In an embodiment, step 516 includes responding to the high voltage control signal by stopping output of the high voltage signal to the electrode, for example, when the high voltage control signal is received from the high voltage control switch. In an embodiment, step 516 includes maintaining output of the high voltage signal, for example, when the high voltage control signal from the high voltage control switch is not received.

In an embodiment, step 504 includes receiving the low voltage signal from an electrode controller.

In an embodiment, step 502 includes operating an electrode controller to output a substantially constant low voltage signal. Additionally or alternatively, step 502 can include operating an electrode controller to output a time-varying low voltage signal. Additionally or alternatively, the step 502 can include operating an electrode controller to output a periodic waveform low voltage signal.

Where the specification or claims refer to isolation or electrical isolation of a particular element, this is to be understood as referring to the absence and prevention of an electrical connection between the particular element and at least a second element. Where the second element is not expressly defined nor implied by the context, the term is to be construed as meaning electrical isolation of the particular element from human contact during normal operation of the associated system, notwithstanding a recognition by the inventors that the absolute prevention of electrical contact may not be possible, inasmuch as most methods of electrical isolation can be defeated by a determined individual.

Additionally, the term isolation includes within its scope a range of structures and methods to achieve electrical isolation, including, for example: positioning an intervening mechanical structure between the elements to be isolated; positioning the particular element within an enclosure so as to be substantially inaccessible to unintended human contact; enclosing or partially enclosing the particular element within an electrically insulating cover or housing; positioning the particular element within an electrically conductive enclosure that is coupled to ground and structured such that attempted contact by a human with the particular element will necessarily bring that element first into contact with the enclosure so as to shunt to ground any voltage potential that may be present; etc.

Finally, electrical isolation is not limited to perfect isolation, but also includes within its scope isolation that is not perfect, i.e., isolation in which a minute and negligible electrical current may be present. Likewise, with respect to electrical isolation that includes the presence of an electrical insulator or electrical insulation, such terms are to be construed as including with their scope materials that may have a minute and negligible conductance value.

Where the specification or claims refer to applying electrical energy to a combustion reaction, this is to be construed as including within its scope, applying any of a voltage, a charge, or an electric field to the combustion reaction or proximate to the combustion reaction. Where the claims recite accessible volume, this is to be construed as referring to a volume that is accessible to human adults.

The abstract of the present disclosure is provided as a brief outline of some of the principles of the invention according to one embodiment, and is not intended as a complete or definitive description of any embodiment thereof, nor should it be relied upon to define terms used in the specification or claims. The abstract does not limit the scope of the claims.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. 

1. A system for applying electrical energy to a combustion reaction, comprising: an electrode configured to apply electrical energy to a combustion reaction; a step-up voltage converter configured to receive a low voltage signal on an input node, convert the low voltage signal to a high voltage signal of 1000 volts or more, and output the high voltage signal on an output node; and a close electrical coupling between the output node of the step-up voltage converter and the electrode.
 2. The system for applying electrical energy to a combustion reaction of claim 1, wherein the step-up voltage converter includes a voltage multiplier. 3-7. (canceled)
 8. The system for applying electrical energy to a combustion reaction of claim 7, wherein the step-up voltage converter is configured to receive the low voltage signal of 120 volts or less from the electrode controller.
 9. The system for applying electrical energy to a combustion reaction of claim 8, wherein the step-up voltage converter is configured to receive the low voltage signal of 12 volts or less from the electrode controller.
 10. The system for applying electrical energy to a combustion reaction of claim 9, wherein the step-up voltage converter is configured to receive the low voltage signal of 5 volts or less from the electrode controller.
 11. The system for applying electrical energy to a combustion reaction of claim 1, further comprising: the electrode controller operatively coupled to the step-up voltage converter.
 12. The system for applying electrical energy to a combustion reaction of claim 11, further comprising: a low voltage cable configured to carry the low voltage signal from the electrode controller to the step-up voltage converter.
 13. The system for applying electrical energy to a combustion reaction of claim 12, wherein the low voltage cable further comprises: a first low voltage conductor configured to carry current corresponding to the low voltage signal from the electrode controller to the step-up voltage converter; and a second low voltage conductor configured to carry current corresponding to the low voltage signal from the step-up voltage converter to the electrode controller; wherein the first and second low voltage conductors are configured to minimize stored magnetic energy corresponding to the current carried by the low voltage cable.
 14. The system for applying electrical energy to a combustion reaction of claim 12, wherein the first and second low voltage conductors are configured to minimize stored magnetic energy corresponding to the current carried by the low voltage cable by being placed within 1 centimeter of one another along a majority of their respective lengths.
 15. The system for applying electrical energy to a combustion reaction of claim 12, wherein the first and second low voltage conductors are configured to minimize stored magnetic energy corresponding to the current carried by the low voltage cable by having respective high aspect ratio cross-sections of 2:1 or greater, and with longer dimensions abutting one another.
 16. The system for applying electrical energy to a combustion reaction of claim 11, wherein the electrode controller is configured to output a substantially constant low voltage signal.
 17. The system for applying electrical energy to a combustion reaction of claim 11, wherein the electrode controller is configured to output a time-varying low voltage signal.
 18. The system for applying electrical energy to a combustion reaction of claim 1, wherein the high voltage signal has a voltage of 5000 volts or more.
 19. The system for applying electrical energy to a combustion reaction of claim 18, wherein the high voltage signal has a voltage of 10,000 volts or more.
 20. The system for applying electrical energy to a combustion reaction of claim 19, wherein the high voltage signal has a voltage of 40,000 volts or more.
 21. The system for applying electrical energy to a combustion reaction of claim 1, wherein the high voltage signal has a negative voltage of magnitude 1000 volts or more.
 22. The system for applying electrical energy to a combustion reaction of claim 21, wherein the high voltage signal has a negative voltage of magnitude 5000 volts or more.
 23. The system for applying electrical energy to a combustion reaction of claim 22, wherein the high voltage signal has a negative voltage of magnitude 10,000 volts or more.
 24. The system for applying electrical energy to a combustion reaction of claim 23, wherein the high voltage signal has a negative voltage of magnitude 40,000 volts or more. 25-27. (canceled)
 28. The system for applying electrical energy to a combustion reaction of claim 1, wherein the step-up voltage converter is configured for mounting on or near a combustor or burner wall; wherein the electrode or a connection in electrical continuity with the electrode is configured to penetrate the combustor or burner wall to cause at least a portion of the electrode to be in proximity to the combustion reaction; and wherein the close electrical coupling includes a high voltage cable configured to carry the high voltage signal from the output node to the electrode or the connection in electrical continuity with the electrode; and further comprising: an electrically isolating housing configured to isolate the high voltage cable from a region separated from the combustion reaction by the combustor or burner wall.
 29. The system for applying electrical energy to a combustion reaction of claim 1, further comprising: an electrically isolating housing; and wherein the close electrical coupling includes a high voltage electrical connection that is substantially contained by the electrically isolating housing.
 30. (canceled)
 31. The system for applying electrical energy to a combustion reaction of claim 1, further comprising: a high voltage control switch configured to cause the step-up voltage converter not to output the high voltage to the conductive output surface when the electrically isolating housing is moved from a position that isolates the high voltage signal from the accessible volume.
 32. The system for applying electrical energy to a combustion reaction of claim 1, wherein the electrode includes a conductive electrode surface configured to receive the high voltage.
 33. The system for applying electrical energy to a combustion reaction of claim 1, wherein the electrode includes an electrode coupling feature; and wherein the close electrical coupling includes a close electrical coupling feature configured to receive the electrode coupling feature.
 34. The system for applying electrical energy to a combustion reaction of claim 33, wherein the electrode coupling feature includes a prong.
 35. The system for applying electrical energy to a combustion reaction of claim 33, wherein the close electrical coupling feature includes a socket.
 36. The system for applying electrical energy to a combustion reaction of claim 33, wherein the close electrical coupling feature includes an electrically conductive output surface configured to hold or be held in a contacting relationship with the electrode coupling feature.
 37. The system for applying electrical energy to a combustion reaction of claim 1, wherein the electrode includes a conductive electrode surface configured to receive the high voltage; and wherein the close coupling further comprises: a conductive output surface configured to output the high voltage; and a high voltage control switch configured to cause the step-up voltage converter not to output the high voltage to the conductive output surface when at least a portion of the conductive electrode surface is not in contact with at least a portion of the conductive output surface.
 38. The system for applying electrical energy to a combustion reaction of claim 1, further comprising: a high voltage control switch including a momentary switch configured to be held normally open when at least a portion of the conductive electrode surface is not in contact with at least a portion of the conductive output surface or when the high voltage signal is not isolated from an accessible volume. 39-44. (canceled)
 45. The system for applying electrical energy to a combustion reaction of claim 1, wherein the electrode includes a conductive electrode surface configured to receive the high voltage; and wherein the close coupling further comprises: a conductive output surface configured to output the high voltage; and a high voltage control switch configured to cause the close coupling not to output the high voltage to the conductive output surface when at least a portion of the conductive electrode surface is not in contact with at least a portion of the conductive output surface.
 46. A method for applying electrical energy to a combustion reaction, comprising: receiving a low voltage signal at an input node; converting the low voltage signal to a high voltage signal of 1000 volts or more; outputting the high voltage signal on an output node for an electrode configured to carry the high voltage signal to or to proximity with a combustion reaction; and isolating the high voltage signal from a human-accessible volume separated from the combustion reaction by a combustor or burner wall. 47-49. (canceled)
 50. The method for applying electrical energy to a combustion reaction of claim 46, wherein converting the low voltage signal to a high voltage signal of 1000 volts or more includes operating a voltage multiplier. 51-52. (canceled)
 53. The method for applying electrical energy to a combustion reaction of claim 52, wherein receiving the low voltage signal at an input node includes receiving a voltage signal of 12 volts or less.
 54. The method for applying electrical energy to a combustion reaction of claim 53, wherein receiving the low voltage signal at an input node includes receiving a voltage signal of 5 volts or less.
 55. The method for applying electrical energy to a combustion reaction of claim 46, wherein receiving the low voltage signal at an input node includes receiving the low voltage signal from an electrode controller.
 56. The method for applying electrical energy to a combustion reaction of claim 46, further comprising: outputting the low voltage signal from an electrode controller.
 57. The method for applying electrical energy to a combustion reaction of claim 56, wherein outputting the low voltage signal from the electrode controller includes outputting a substantially constant low voltage signal.
 58. The method for applying electrical energy to a combustion reaction of claim 56, wherein outputting the low voltage signal from the electrode controller includes outputting a time-varying low voltage signal. 59-65. (canceled)
 66. The method for applying electrical energy to a combustion reaction of claim 46, further comprising: carrying the high voltage signal from the output node to the electrode via a close electrical coupling.
 67. The method for applying electrical energy to a combustion reaction of claim 66, wherein the close electrical coupling is configured prevent high voltage exposure to a volume at least intermittently occupied by a person. 68-69. (canceled)
 70. The method for applying electrical energy to a combustion reaction of claim 66, wherein converting the low voltage signal to a high voltage signal includes converting the low voltage signal to a high voltage signal with a step-up voltage converter configured for mounting on or near a combustor or burner wall; wherein the electrode or a connection in electrical continuity with the electrode is configured to penetrate the combustor or burner wall to cause at least a portion of the electrode to be in proximity to the combustion reaction; wherein carrying the high voltage signal from the output node to the electrode via a close electrical coupling includes carrying the high voltage signal with a high voltage cable to the electrode or the connection in electrical continuity with the electrode; and wherein isolating the high voltage signal includes isolating the high voltage signal with an electrically isolating housing configured to isolate the high voltage cable from the human-accessible region separated from the combustion reaction by a combustor or burner wall.
 71. The method for applying electrical energy to a combustion reaction of claim 66, wherein isolating the high voltage signal from a human-accessible volume separated from the combustion reaction by a combustor or burner wall includes housing the step-up voltage converter in or behind an electrically isolating housing; and carrying the high voltage signal from the output node to the electrode via a close electrical coupling includes carrying the high voltage signal from the output node to the electrode via a high voltage electrical connection that is substantially contained by the electrically isolating housing. 72-76. (canceled)
 77. The method for applying electrical energy to a combustion reaction of claim 66, wherein carrying the high voltage signal from the output node to the electrode via a close electrical coupling includes carrying the high voltage signal on an output node including a shielded cable.
 78. The method for applying electrical energy to a combustion reaction of claim 66, wherein carrying the high voltage signal from the output node to the electrode via a close electrical coupling includes carrying the high voltage signal on an output node including a high voltage electrical connection that is substantially contained by the electrically isolating housing.
 79. The method for applying electrical energy to a combustion reaction of claim 46, further comprising: receiving a high voltage control signal at a high voltage control switch configured to respond when isolation of a node carrying the high voltage signal from a volume separated from the combustion reaction by a combustor or burner wall is interrupted.
 80. The method for applying electrical energy to a combustion reaction of claim 79, further comprising: responding to the high voltage control signal by stopping output of the high voltage signal to the electrode when the high voltage control signal is received from the high voltage control switch. 81-84. (canceled)
 85. The method for applying electrical energy to a combustion reaction of claim 46, further comprising: operating an electrode controller to output a substantially constant low voltage signal.
 86. The method for applying electrical energy to a combustion reaction of claim 46, further comprising: operating an electrode controller to output a time-varying low voltage signal. 